A bit tangential to the main topic, but I can't wait for that book to be out. IIRC (I read it somewhere??) it's based on his 'Robust Systems' thoughts and experiments.

Total mystery here: https://mitpress.mit.edu/books/software-design-flexibility

You can dip your toe here: https://groups.csail.mit.edu/mac/users/gjs/6.945/readings/